Meridian Unplugged - Powered by MrTechGuy.co.uk Forums Discussion Meridian - Systems G68 multiple subs setup w Velodyne sms-1

Hello - I've just purchased a G68XXV and I'm wondering what is the best sub configuration considering G68 has MRC. I have three subs (analog active) in various parts of the room to cancel room effects. I currently us the SMS-1 for finer low end calibration.

Would it be better to configure the G68 with one sub out to a calibrated SMS/sub system then apply MRC OR connect three subs direct to G68?

Hi there Halej,

IMO, MRC can be improved upon at subwoofer frequencies. MRC is effective but fairly subtle. Accurately applied parametric EQ can really step-up the performance of your subwoofer system. That being said, the SMS-1 is a great little device but its handy on-screen measurement system is its weakest point and it has other shortcomings when it comes to owners of multi-sub systems.

The SMS-1 only displays frequency response and that display has been 1/3 octave smoothed. This makes it difficult to determine which peaks n' valleys are due to your room's low frequency modal behavior (sharply defined peaks and nulls), which are due to shortcomings in your loudspeaker and subwoofer placement, and which are due to phase and delay/distance differences between all the sources of bass within your room. Affordable software-based acoustic measurement tools such as REW or the Dayton Omnimic are inexpensive and offer far more detail in their frequency vs time waterfall displays. With this additional info and some knowledge of the subject, you can set the SMS-1 much more precisely than is possible with the built-in facility. Coincidentally Meridian's MRC used the same sort of frequency vs time waterfall display to go about doing its thing.


So that brings us to another potential shortcoming of the SMS-1 as applied to your system. It doesn't offer separately adjustable delay on each of it's subwoofer outputs. If you use a single subwoofer or a pair of subs located equidistant from the listening position, then the delay setting in your pre-pro (adjusted to account for the SMS-1's latency) and the SMS-1's phase control will get the job done. However if you are using multiple subs at varying distances from the listening position, you need an EQ processor box that:

• #1)Allows you to perform multiple bands of global parametric EQ on your mono subwoofer channel.
  
  #2)Splits that EQed mono signal into sufficient channels to support each subwoofer which is located at a significantly different sub-to-listening-position distance.
  
  #3)Permits separate delay adjustment of each of those individual subwoofer outputs.

At the moment I'm unaware of any manually adjusted all-in-one consumer product we can add to our M pre-pros and that can accommodate all these requirements. The SVS and Audyssey stand alone automated sub EQ boxes offer two separately adjusted sub outs but personally, I prefer the control of doing the adjustments myself. So if you want to ideally setup your subs you need to resort to a loudspeaker controller/processor from the pro audio world. There you can find a myriad of DSP based all-in one boxes which can be configured to achieve our needs. Checkout the QSC DSP-30, DBX Driverack 260, and any of the Xilica processors. You will still need that software based measurement system like REW or the Omnimic, but with these tools, you can really do justice to your high-end setup.

Happy Trails!
MTB Vince

Thank you, Vince sounds like you've been through this before. All that being said I think I've come to the limit of the WAF (wife acceptance factor) by purchasing the G68. Maybe I could sneek in the software but another box is going to be awhile.

With that said, what would you recommend for this multi sub set-up?

BTW - how do you link the software adjustment to the SMS or the G68?

Thank you for the info.

REW and Omnimic are simply more accurate, fully featured measurement systems that greatly improve upon the included minimalist on-screen display measurement facility found in your SMS-1. Much like the that the SMS-1 offers but more accurate (less pretty looking results! ), REW and Omnimic allow you to see the problems more clearly and that combined with a more thorough understanding of the subject matter allows you to better isolate the source of the problem so as to address it properly. Based on what you see, you can adjust placement of subwoofer and loudspeaker positions, set individual delays, and then manually apply parametric EQ to tidy up the remaining problems. All the pro audio loudspeaker processor/EQ boxes I mentioned are about the same size as your SMS-1. The measurement systems use a mic much like your SMS-1, but the measurements are taken by your computer and displayed there rather than on your tv screen.

Oh BTW, if you were using the SMS-1's auto EQ function- STOP THAT RIGHT NOW! It works crap compared to manual operation.

Happy Trails!
MTB Vince

Vince - Great info-- I downloaded the REW software and the setup looks pretty straight forward. Am I correct that this only provides a measurement tool? and an opportunity to measure certain set-ups and adjust (by other means) as neccessary. BTW the calibration curves for SPL meters is worth using it alone.

John

PS - I do use auto adjustment on my SMS but only to get in the ball park then I complete by manual adjustment.